Keithley 642 Electrometer, 10aA - 200nA

Keithley 642 Electrometer

The Keithley 642 is a direct-reading MOSFET-based electrometer, designed for the sensitive measurement of current, voltage, and charge. This state-of-the-art device is ideal for labs that require precision and accuracy in their measurements.

Key Features and Specifications

• Sensitivity: 10^-17A (10 aA) for ultra-sensitive applications.
• Dynamic Range: Offers over 100,000:1 linear dynamic range at analog output, making it versatile for diverse measurements.
• Fast Response: Features a 22 msec. time constant on the 10^-10A range for rapid analysis.
• Current Measurement Range: 10 aA to 200 nA with a typical voltage burden of less than 1 mV.
• Voltage Reading Capabilities: Measures 10 µV to 10 V with an impressive 10,000 TΩ input resistance.
• Charge Measurement: Capable of measuring charge from 800 aC to 100 pC, providing flexibility in applications.
• Maximum Sensitivity: Achieved in CHARGE mode by integrating current applied to the input.
• High Resolution:
  • Digital format allows for detection of subtle changes in large signals with a resolution up to 1 part in 20,000.
  • Feedback output exhibits low noise and non-linearity (≤ 5 ppm).
  • Wide dynamic range ensures consistent gain across the full span, negating the need for range changes.
• Advanced Design:
  • Employs specially packaged dual monolithic MOSFET with compensated temperature coefficient within a guarded package.
  • Remote head design minimizes active input volume for enhanced sensitivity.
  • Sealed remote head features desiccant paper to maintain low internal humidity for improved performance.
  • Direct-coupled circuit preamplifier boasts a single, controlled time constant.
  • ZERO CHECK switching mechanism facilitates minimal charge transfer (typically < 10 fC).
• Versatile Analog Outputs:
  • FEEDBACK Output: Delivers the highest precision, widest dynamic range (over 10⁵), lowest noise, and fastest speed.
  • 1V / 10,000 COUNTS Output: Normalizes the output to 1V per 10,000 counts irrespective of range, ensuring consistency.
  • 1V / 100 COUNTS Output: Especially useful for sensitive measurements, allowing 1V to correspond to 100 counts for better signal amplification.